Kisspeptin-10 inhibits stromal-derived factor 1-induced invasion of human endometrial cancer cells

Kisspeptin Regulates Cell Invasion and Migration in Endometrial Cancer

Kisspeptin (a product of the KISS1 gene and its receptor) plays an important role in obstetrics, gynecology, and cancer cell metastasis and behavior. In hypothalamic-pituitary-gonadal axis and placentation, Kisspeptin/Kisspeptin receptor affects hormone release and represses trophoblast invasion into maternal deciduae. Endometrial cancer is one of the common gynecological cancers and is usually accompanied by metastasis, the risk factor that causes death. Recently, research has demonstrated that Kisspeptin/Kisspeptin receptor expression in aggressive-stage endometrial cancer tissues. However, the detailed mechanism of Kisspeptin/Kisspeptin receptor in regulating the motility of endometrial cancers is not well understood. In this study, we use endometrial cancer cell lines RL95-2, Ishikawa, HEC-1-A, and HEC-1-B as models to explore the molecular mechanism of Kisspeptin on cell motility. First, we discovered that Kisspeptin/Kisspeptin receptor was expressed in endometrial cancer cells, and Kisspeptin significantly regulated the migration and invasion of endometrial cancer cells. Furthermore, we explored the epithelial-mesenchymal transition marker expression and the underlying signals were regulated on Kisspeptin treatment. In conclusion, we suggest that Kisspeptin regulates endometrial cancer cell motility via FAK and Src expression and the ERK1/2, N-Cadherin, E-Cadherin, beta-Catenin, Twist, and matrix metalloproteinase signaling pathways. We expect these molecules could be candidates for the development of new approaches and therapeutic targets.

KISS1 and Kisspeptins Detection in Cell Lines

KISS1 belongs to the family of metastasis suppressor genes. However, its role is not limited to blocking cancer metastasis. KISS1 and its by-product kisspeptins (KP) are important players in regulating the reproductive axis in different species and have new roles in controlling physiological balance and social behaviors. These diverse functions point to KISS1 as a potential therapeutic molecule. Here we describe a methodology to detect KISS1 and KP from cell lysate and conditioned media in cell lines. This will serve as a critical tool to study KISS1 processing in KP.

Metastases and Recurrence Risk Factors in Endometrial Cancer-The Role of Selected Molecular Changes, Hormonal Factors, Diagnostic Methods and Surgery Procedures

The presence of metastatic endometrial cancer (EC) is a key problem in treatment failure associated with reduced overall survival rates. The most common metastatic location is the pelvic lymph nodes, and the least common is the brain. The presence of metastasis depends on many factors, including the molecular profile of cancer (according to the TCGA-Genome Atlas), the activity of certain hormones (estrogen, prolactin), and pro-inflammatory adipocytokines. Additionally, an altered expression of microRNAs affecting the regulation of numerous genes is also related to the spread of cancer. This paper also discusses the value of imaging methods in detecting metastases; the primary role is attributed to the standard transvaginal USG with the tumor-free distance (uTFD) option. The influence of diagnostic and therapeutic methods on EC spread is also described. Hysteroscopy, according to the analysis discussed above, may increase the risk of metastases through a fluid medium, mainly performed in advanced stages of EC. According to another analysis, laparoscopic hysterectomy performed with particular attention to avoiding risky procedures (trocar flushing, tissue traumatization, preserving a margin of normal tissue) was not found to increase the risk of EC dissemination.

Physiological and pathological roles of locally expressed kisspeptin and KISS1R in the endometrium

Kisspeptins, encoded by the KISS1 gene, are a family of polypeptides that bind the kisspeptin receptor (KISS1R) to perform biological functions. Produced mainly in the hypothalamus, these neuropeptides regulate the pulsatile secretion of GnRH and trigger the hypothalamus-pituitary-gonadal axis. Other peripheral organs also express kisspeptin, which inhibits metastasis. Kisspeptin and KISS1R are reportedly present in the endometrium and may play roles in limiting the migration and invasion of trophoblasts into the endometrium during pregnancy (decidua) to maintain endometrial homeostasis. A deficiency of kisspeptin and KISS1R in the endometrium can lead to pathological conditions such as endometriosis and endometrial carcinoma. Kisspeptin and KISS1R in the endometrium can also promote endometrial receptivity and decidualization. Overall, kisspeptin and KISS1R are important for maintaining the normal physiological functions of the endometrium. By summarizing the roles of kisspeptin and KISS1R in the endometrium, our review explores the regulatory roles in the peripheral reproductive system of this peptide family that plays broad and profound roles in many physiological processes.

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Kisspeptin and GPR54 Receptor Expression in Endometrial Cancer Tissue

Kisspeptin (KISS) is a natural peptide-discovered in 1996 as a factor inhibiting the ability to metastasize in malignant melanoma. This protein plays also a regulatory role in the process of puberty, the menstrual cycle, spermatogenesis, implantation and development of the human placenta. The present study aimed to evaluate the expression of KISS and its receptor GPR54 in endometrial cancer (EC) tissue, depending on the histological type of cancer, its stage, various demographic characteristics, and clinical conditions in 214 hysterectomy patients. Expression of KISS and GPR54 was confirmed in 99.5% and 100% of the cases, respectively. Hormone replacement therapy and the coexistence of the anti-Müllerian type 2 receptor in cancer tissue enhanced KISS expression. Smoking, on the other hand, decreased KISS expression. GPR54 expression increased with the advancement of the disease (according to FIGO classification). Also, the presence of the anti-Müllerian type 2 receptor in EC increased the level of GPR54. Hypertension, age and miscarriage harmed the presence of GPR54. The histological type of cancer, diabetes type 2, body mass index, hormonal contraception, number of deliveries, birth weight of newborns, breastfeeding time, and the presence of AMH in EC tissue were not associated with the expression of either KISS nor GPR54. The KISS level was also significantly related to the GPR54 level. Considering that KISS is a non-toxic peptide with antimetastatic properties, further investigation is essential to determine the clinical significance of this peptide.

The Exploration of Chemokines Importance in the Pathogenesis and Development of Endometrial Cancer

Endometrial cancer (EC) is one of the most frequent female malignancies. Because of a characteristic symptom, vaginal bleeding, EC is often diagnosed in an early stage. Despite that, some EC cases present an atypical course with rapid progression and poor prognosis. There have been multiple studies conducted on molecular profiling of EC in order to improve diagnostics and introduce personalized treatment. Chemokines-a protein family that contributes to inflammatory processes that may promote carcinogenesis-constitute an area of interest. Some chemokines and their receptors present alterations in expression in tumor microenvironment. CXCL12, which binds the receptors CXCR4 and CXCR7, is known for its impact on neoplastic cell proliferation, neovascularization and promotion of epidermal-mesenchymal transition. The CCL2-CCR2 axis additionally plays a pivotal role in EC with mutations in the LKB1 gene and activates tumor-associated macrophages. CCL20 and CCR6 are influenced by the RANK/RANKL pathway and alter the function of lymphocytes and dendritic cells. Another axis, CXCL10-CXCR3, affects the function of NK-cells and, interestingly, presents different roles in various types of tumors. This review article consists of analysis of studies that included the roles of the aforementioned chemokines in EC pathogenesis. Alterations in chemokine expression are described, and possible applications of drugs targeting chemokines are reviewed.

Adipocytokines and disease progression in endometrial cancer: a systematic review

The objective of the study was to document the effect of adipocytokines on endometrial cancer progression. A search of the databases CINAHL, Medline, PubMed, Cochrane, Web of Science, Embase and Google Scholar was performed for English language articles from January 2000 to December 2020 using the keywords: (Endometrial cancer) AND (progression OR metastasis) AND (adipocytokine OR adiponectin OR leptin OR visfatin OR IL-6 OR TNF-α OR adipokine OR cytokine). Forty-nine studies on adipocytokines have been included in this review. Adiponectin has been linked with anti-proliferative and anti-metastatic effects on endometrial cancer cells and is associated with a better prognosis. Leptin, visfatin and resistin are linked to the stimulation of endometrial cancer growth, proliferation, invasion and metastasis and are associated with worse prognosis or with a higher grade/stage of endometrial cancer. IL-6, Il-11, IL-31, IL-33, TNF-α, TGF-β1, SDF-1 and CXCR are involved in endometrial cancer cell growth and metastasis or involved in epithelial mesenchymal transformation (EMT) or associated with advanced disease. Adipocytokines have been found to directly impact endometrial cancer cell proliferation, invasion and migration. These molecules and their signalling pathways may be used to determine prognosis and course of the disease and may also be exploited as potential targets for cancer treatment and prevention of progression.

KISS1 in metastatic cancer research and treatment: potential and paradoxes

The significance of KISS1 goes beyond its original discovery as a metastasis suppressor. Its function as a neuropeptide involved in diverse physiologic processes is more well studied. Enthusiasm regarding KISS1 has cumulated in clinical trials in multiple fields related to reproduction and metabolism. But its cancer therapeutic space is unsettled. This review focuses on collating data from cancer and non-cancer fields in order to understand shared and disparate signaling that might inform clinical development in the cancer therapeutic and biomarker space. Research has focused on amino acid residues 68-121 (kisspeptin 54), binding to the KISS1 receptor and cellular responses. Evidence and counterevidence regarding this canonical pathway require closer look at the covariates so that the incredible potential of KISS1 can be realized.

The KiSS-1/GPR54 system: Essential roles in physiological homeostasis and cancer biology

KiSS-1, first identified as an anti-metastasis gene in melanoma, encodes C-terminally amidated peptide products, including kisspeptin-145, kisspeptin-54, kisspeptin-14, kisspeptin-13 and kisspeptin-10. These products are endogenous ligands coupled to G protein-coupled receptor 54 (GPR54)/hOT7T175/AXOR12. To date, the regulatory activities of the KiSS-1/GPR54 system, such as puberty initiation, antitumor metastasis, fertility in adulthood, hypothalamic-pituitary-gonadal axis (HPG axis) feedback, and trophoblast invasion, have been investigated intensively. Accumulating evidence has demonstrated that KiSS-1 played a key role in reproduction and served as a promising biomarker relative to the diagnosis, identification of therapeutic targets and prognosis in various carcinomas, while few studies have systematically summarized its subjective factors and concluded the functions of KiSS-1/GPR54 signaling in physiology homeostasis and cancer biology. In this review, we retrospectively summarized the regulators of the KiSS-1/GPR54 system in different animal models and reviewed its functions according to physiological homeostasis regulations and above all, cancer biology, which provided us with a profound understanding of applying the KiSS-1/GPR54 system into medical applications.

Role of the tumor microenvironment in regulating the anti-metastatic effect of KISS1

KISS1, a metastasis suppressor gene, has been shown to block metastasis without affecting primary tumor formation. Loss of KISS1 leads to invasion and metastasis in multiple cancers, which is the leading cause of cancer morbidity and mortality. The discovery of KISS1 has provided a ray of hope for early clinical diagnosis and for designing effective treatments targeting metastatic cancer. However, this goal requires greater holistic understanding of its mechanism of action. In this review, we go back into history and highlight some key developments, from the discovery of KISS1 to its role in regulating multiple physiological processes including cancer. We discuss key emerging roles for KISS1, specifically interactions with tissue microenvironment to promote dormancy and regulation of tumor cell metabolism, acknowledged as some of the key players in tumor progression and metastasis. We finally discuss strategies whereby KISS1 might be exploited clinically to treat metastasis.

Autocrine production of reproductive axis neuropeptides affects proliferation of canine osteosarcoma in vitro

Background

Osteosarcoma strikes hundreds of people each year, of both advanced and younger ages, and is often terminal. Like many tumor types, these bone tumors will frequently undergo a neuroendocrine transition, utilizing autocrine and/or paracrine hormones as growth factors and/or promoters of angiogenesis to facilitate progression and metastasis. While many of these factors and their actions on tumor growth are characterized, some tumor-derived neuropeptides remain unexplored.

Methods

Using validated canine osteosarcoma cell lines in vitro, as well as cells derived from spontaneous tumors in dogs, we explored the autocrine production of two neuropeptides typically found in the hypothalamus, and most closely associated with reproduction: gonadotropin-releasing hormone (GnRH) and kisspeptin (Kiss-1). We evaluated gene expression and protein secretion of these hormones using quantitative RT-PCR and a sensitive radioimmunoassay, and explored changes in cell proliferation determined by MTS cell viability assays.

Results

Our current studies reveal that several canine osteosarcoma cell lines (COS, POS, HMPOS, D17, C4) synthesize and secrete GnRH and express the GnRH receptor, while COS and POS also express kiss1 and its cognate receptor. We have further found that GnRH and kisspeptin, exogenously applied to these tumor cells, exert significant effects on both gene expression and proliferation. Of particular interest, kisspeptin exposure stimulated GnRH secretion from COS, similarly to the functional relationship observed within the neuroendocrine reproductive axis. Additionally, GnRH and kisspeptin treatment both increased COS proliferation, which additionally manifested in increased expression of the bone remodeling ligand rankl within these cells. These effects were blocked by treatment with a specific GnRH receptor inhibitor. Both neuropeptides were found to increase expression of the specific serotonin (5HT) receptor htr2a, the activation of which has previously been associated with cellular proliferation, suggesting that production of these factors by osteosarcoma cells may act to sensitize tumors to circulating 5HT of local and/or enteric origin.

Conclusions

Here we report that kisspeptin and GnRH act as autocrine growth factors in canine osteosarcoma cells in vitro, modulating RANKL and serotonin receptor expression in a manner consistent with pro-proliferative effects. Pharmacological targeting of these hormones may represent new avenues of osteosarcoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5363-4) contains supplementary material, which is available to authorized users.

The role of neuropeptides and neurotransmitters on kisspeptin/kiss1r-signaling in female reproduction

Reproductive function is regulated by the hypothalamic-pituitary-gonads (HPG) axis. Hypothalamic neurons synthesizing kisspeptin play a fundamental role in the central regulation of the timing of puberty onset and reproduction in mammals. Kisspeptin is a regulator of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH). In female rodent, the kisspeptin (encoded by kiss1 gene), neurokinin B (Tac3) and dynorphin neurons form the basis for the "KNDy neurons" in the arcuate nucleus and play a fundamental role in the regulation of GnRH/LH release. Furthermore, various factors including neurotransmitters and neuropeptides may cooperate with kisspeptin signaling to modulate GnRH function. Many neuropeptides including proopiomelanocortin, neuropeptide Y, agouti-related protein, and other neuropeptides, as well as neurotransmitters, dopamine, norepinephrine and γ-aminobutyric acid are suggested to control feeding and HPG axis, the underlying mechanisms are not well known. Nonetheless, to date, information about the neurochemical factors of kisspeptin neurons remains incomplete in rodent. This review is intended to provide an overview of KNDy neurons; major neuropeptides and neurotransmitters interfere in kisspeptin signaling to modulate GnRH function for regulation of puberty onset and reproduction, with a focus on the female rodent.

Recombinant Lactococcus lactis NZ9000 secretes a bioactive kisspeptin that inhibits proliferation and migration of human colon carcinoma HT-29 cells

Background

Proteinaceous bioactive substances and pharmaceuticals are most conveniently administered orally. However, the facing problems are the side effects of proteolytic degradation and denaturation in the gastrointestinal tract. In recent years, lactic acid bacteria (LAB) have been verified to be a promising delivery vector for susceptible functional proteins and drugs. KiSS-1 peptide, a cancer suppressor, plays a critical role in inhibiting cancer metastasis and its activity has been confirmed by direct administration. However, whether this peptide can be functionally expressed in LAB and exert activity on cancer cells, thus providing a potential alternative administration manner in the future, has not been demonstrated.

Results

A recombinant Lactococcus lactis strain NZ9000-401-kiss1 harboring a plasmid containing the gene of the tumor metastasis-inhibiting peptide KiSS1 was constructed. After optimization of the nisin induction conditions, the recombinant strain efficiently secreted KiSS1 with a maximum detectable amount of 27.9 μg/ml in Dulbecco’s Modified Eagle medium. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide and would healing assays, respectively, indicated that the secreted KiSS1 peptide remarkably inhibited HT-29 cell proliferation and migration. Furthermore, the expressed KiSS1 was shown to induce HT-29 cell morphological changes, apoptosis and reduce the expression of matrix metalloproteinase 9 (MMP-9) at both mRNA and protein levels.

Conclusions

A recombinant L. lactis NZ9000-401-kiss1 successfully expressing the human kiss1 was constructed. The secreted KiSS1 peptide inhibited human HT-29 cells’ proliferation and migration probably by invoking, or mediating the cell-apoptosis pathway and by down regulating MMP-9 expression, respectively. Our results suggest that L. lactis is an ideal cell factory for secretory expression of tumor metastasis-inhibiting peptide KiSS1, and the KiSS1-producing L. lactis strain may serve as a new tool for cancer therapy in the future.

Cancer-associated fibroblasts promote the progression of endometrial cancer via the SDF-1/CXCR4 axis

Background

Cancer-associated fibroblasts (CAFs) are believed to play an essential role in cancer initiation and development. However, little research has been undertaken to evaluate the role of CAFs in endometrial cancer (EC) progression. We aim to detect the functional contributions of CAFs to promote progression of EC.

Methods

Stromal fibroblasts were isolated from endometrioid adenocarcinomas and normal endometrial tissues. The conditioned media of cultured CAFs and normal fibroblasts (NFs) were collected to detect the level of stromal cell-derived factor-1alpha (SDF-1α), macrophage chemoattractant protein-1 (MCP-1), migration inhibitory factor (MIF), colony stimulating factor-1 (CSF-1), and interleukin-1 (IL-1) by ELISA. The CAFs or NFs were cocultured with EC cell lines to determine the proliferation, migration, and invasion by MTT assays and transwell chambers. Xenograft models were used to observe tumor growth. Matrix metalloproteinases (MMP)-2 and MMP-9 activity was evaluated by zymography. AMD3100 (a chemokine receptor 4 (CXCR4) antagonist) was used to block the SDF-1/CXCR4 axis. Neutralizing antibodies were used to detect PI3K/Akt and MAPK/Erk pathways by western blotting. SDF-1α and CXCR4 expressions were analyzed in xenotransplanted tumors and 348 cases by immunohistochemistry.

Results

CAFs promoted proliferation, migration, and invasion as well as in vivo tumorigenesis of admixed EC cells significantly more than NFs by secreting SDF-1α. These effects were significantly inhibited by AMD3100. CAFs promoted EC progression via the SDF-1α/CXCR4 axis to activate the PI3K/Akt and MAPK/Erk signalings in a paracrine-dependent manner or increase MMP-2 and MMP-9 secretion in an autocrine-dependent manner. SDF-1α and CXCR4 expression upregulation accompanied clinical EC development and progression. High SDF-1α expression levels were associated with deep myometrial invasion, lymph node metastasis, and poor prognosis in EC.

Conclusions

Our data indicated that CAFs derived from EC tissues promoted EC progression via the SDF-1/CXCR4 axis in a paracrine- or autocrine-dependent manner. SDF-1α is a novel independent poor prognostic factor for EC patients’ survival. Targeting the SDF-1/CXCR4 axis might provide a novel therapeutic strategy for EC treatment.

Tumor progression, metastasis, and modulators of epithelial-mesenchymal transition in endometrioid endometrial carcinoma: an update

Endometrioid endometrial carcinoma (EEC), also known as type 1 endometrial cancer (EC), accounts for over 70-80% of all cases that are usually associated with estrogen stimulation and often develops in a background of atypical endometrial hyperplasia. The increased incidence of EC is mainly confined to this type of cancer. Most EEC patients present at an early stage and generally have a favorable prognosis; however, up to 30% of EEC present as high risk tumors, which have invaded deep into the myometrium at diagnosis and progressively lead to local or extra pelvic metastasis. The poor survival of advanced EC is related to the lack of effective therapies, which can be attributed to poor understanding of the molecular mechanisms underlying the progression of disease toward invasion and metastasis. Multiple lines of evidence illustrate that epithelial-mesenchymal transition (EMT)-like events are central to tumor progression and malignant transformation, endowing the incipient cancer cell with invasive and metastatic properties. The aim of this review is to summarize the current knowledge on molecular events associated with EMT in progression, invasion, and metastasis of EEC. Further, the role of epigenetic modifications and microRNA regulation, tumor microenvironment, and microcystic elongated and fragmented glands like invasion pattern have been discussed. We believe this article may perhaps stimulate further research in this field that may aid in identifying high risk patients within this clinically challenging patient group and also lead to the recognition of novel targets for the prevention of metastasis - the most fatal consequence of endometrial carcinogenesis.

Kisspeptin Activates Ankrd 26 Gene Expression in Migrating Embryonic GnRH Neurons

Kisspeptin, a newly discovered neuropeptide, regulates gonadotropin-releasing hormone (GnRH). Kisspeptins are a large RF-amide family of peptides. The kisspeptin coded by KiSS-1 gene is a 145-amino acid protein that is cleaved to C-terminal peptide kisspeptin-10. G-protein-coupled receptor 54 (GPR54) has been identified as a kisspeptin receptor, and it is expressed in GnRH neurons and in a variety of cancer cells. In this study, enhanced green fluorescent protein (EGFP) labeled GnRH cells with migratory properties, which express GPR54, served as a model to study the effects of kisspeptin on cell migration. We monitored EGFP-GnRH neuronal migration in brain slide culture of embryonic day 14 transgenic rat by live cell imaging system and studied the effects of kisspeptin-10 (1 nM) treatment for 36 h on GnRH migration. Furthermore, to determine kisspeptin-induced molecular pathways related with apoptosis and cytoskeletal changes during neuronal migration, we studied the expression levels of candidate genes in laser-captured EGFP-GnRH neurons by real-time PCR. We found that there was no change in the expression level of genes related to cell proliferation and apoptosis. The expression of ankyrin repeat domain-containing protein (ankrd) 26 in EGFP-GnRH neurons was upregulated by the exposure to kisspeptin. These studies suggest that ankrd 26 gene plays an unidentified role in regulating neuronal movement mediated by kisspeptin-GPR54 signaling, which could be a potential pathway to suppress cell migration.

Inhibition of SDF-1/CXCR4-induced epithelial-mesenchymal transition by kisspeptin-10

Recently we have shown that breast cancer cell invasion was dramatically increased when co-cultured with MG63 cells. In addition we have generated mesenchymal transformed MCF-7 breast cancer cells (MCF-7-EMT), showing significantly increased invasion in contrast to wild type MCF-7 cells (MCF-7 WT). In this study we have analyzed whether stromal derived factor-1 (SDF-1) is responsible for MCF-7 and T-47-D breast cancer cell invasion and epithelial-mesenchymal-transition (EMT). In addition we have analyzed whether kisspeptin-10 (KP-10) treatment affects SDF-1-induced invasion and EMT. Invasion was quantified by assessment of MCF-7 and T-47-D breast cancer cell migration rate through an artificial basement membrane in a modified Boyden chamber during co-culture with MG63 cells or after treatment with SDF-1α, SDF-1β or the combination of both isoforms. Induction of EMT was verified by analysis of protein expression of epithelial marker E-cadherin (CDH1) and mesenchymal markers N-cadherin (CDH2) and Vimentin (VIM). The role of SDF-1 for invasion and induction of EMT in breast cancer cells was analyzed by blocking SDF-1 secretion during co-culture with MG63 cells. In addition effects of KP-10 treatment on SDF-1-induced invasion and EMT were analyzed. Breast cancer cell invasion was significantly increased when co-cultured with MG63 cells. During co-culture SDF-1 protein expression of MG63 cells was significantly induced. The increased breast cancer cell invasion could be blocked by anti-SDF-1 antibodies. Treatment of breast cancer cells in monoculture (without MG63) with SDF-1α, SDF-1β or the combination of both isoforms resulted in a significant escalation of breast cancer cell invasion and induction of EMT. Protein expression of mesenchymal markers CDH2 and VIM was clearly elevated, whereas protein expression of epithelial marker CDH1 was clearly decreased. The SDF-1-induced increase of cell invasion was significantly reduced after treatment with KP-10. In addition, induction of EMT was inhibited. Furthermore, protein expression of the binding site of SDF-1, CXC-motive-chemokine receptor 4 (CXCR-4), was reduced by KP-10. Treatment of MCF-7-EMT cells with KP-10 resulted in a significant drop of cell invasion and CXCR-4 protein expression. Our findings suggest that SDF-1 plays a major role in breast cancer invasion and EMT. SDF-1-induced invasion and EMT can be inhibited by KP-10 treatment by down-regulating CXCR-4 expression.

Estrogen receptor β selective agonists reduce invasiveness of triple-negative breast cancer cells

Metastasis to bone is a frequent problem of advanced breast cancer. Particularly breast cancers, which do not express estrogen receptor α (ERα) and progesterone receptor (PR) and which have no overexpression of human epidermal growth factor receptor 2 (HER2), so-called triple-negative breast cancers (TNBCs), are considered as very aggressive and have a poor prognosis. Recently we have shown that breast cancer cell invasion was dramatically increased when co-cultured with MG63 osteoblast-like cells. Using this model we have now analyzed whether estrogen receptor β (ERβ) plays a role in TNBC cell invasion in vitro. ERα and ERβ protein expression was analyzed using western blot analysis. Invasion was quantified by assessment of TNBC cell migration rate through an artificial basement membrane in a modified Boyden chamber during co-culture with MG63 osteoblast-like cells. The effects of ERβ agonist treatment on CXC motif chemokine receptor 4 (CXCR4) protein expression during co-culture with MG64 cells was quantified using western blot analysis. Proliferation was measured using alamarBlue assay. TNBC cell lines HCC1806 and HCC1937 showed no ERα but high ERβ protein expression. Cell invasion of HCC1806 and HCC1937 TNBC cells was significantly increased when co-cultured with MG63 osteoblast-like cells. Treatment with ERβ selective estrogen agonists liquiritigenin and ERB-041 reduced the ability to invade a reconstituted basement membrane and to migrate in response to the cellular stimulus. During co-culture CXCR4 protein expression of TNBC cell lines HCC1806 and HCC1937 was significantly increased. Treatment with liquiritigenin resulted in a significant decrease of CXCR4 protein expression. Both ERβ agonists showed no effect on TNBC cell proliferation. Our findings suggest that ERβ plays a major role in TNBC invasion. Bone-directed invasion can be inhibited by ERβ agonists.

Generation of MCF-7 cells with aggressive metastatic potential in vitro and in vivo

Epithelial-mesenchymal transition (EMT) is a cellular development program characterized by loss of cell adhesion and increased cell mobility. It is essential for numerous processes including metastasis. In this study we have generated "aggressive" MCF-7 breast cancer cells (MCF-7-EMT), which show significantly increased invasion in contrast to wild type MCF-7 (MCF-7 WT) cells. In addition, we have analyzed, whether these cell lines differ in their metastatic behavior in vivo and in expression of invasion and/or EMT-relevant genes. Invasive behavior of different human breast cancer cell lines was tested. "Aggressive" MCF-7 cells (MCF-7-EMT) were generated using coculture and mammosphere culture techniques. To analyze whether or not MCF-7-EMT cells in contrast to MCF-7 WT cells form metastases in vivo, we assessed metastases in a nude mouse model. mRNA expression profiles of MCF-7 WT cells and MCF-7-EMT cells were compared using the Affymetrix micro array technique. Expression of selected genes was validated using real-time PCR. In addition, protein expression of epithelial marker E-cadherin (CDH1) and mesenchymal markers N-cadherin (CDH2), Vimentin (VIM), and TWIST was compared. The breast cancer cell lines showed different invasive behavior from hardly any invasion to a stronger cell movement. Coculture with osteoblast-like MG63 cells led to significantly increased cell invasion rates. The highest increase was shown using MCF-7 WT cells. Generated MCF-7-EMT cells showed significantly increased invasion as compared to MCF-7 WT cells. In 8 of 10 mice bearing orthotopically growing MCF-7-EMT tumors, we could detect metastases in liver and lung. In mice bearing MCF-7 WT tumors (n = 10), no metastases were found. MCF-7 WT cells and MCF-7-EMT cells were different in expression of 325 genes. Forty-four of the most regulated 50 invasion and/or EMT-related genes were upregulated and 6 genes were downregulated in MCF-7-EMT cells. Protein expression of mesenchymal markers CDH2, VIM, and TWIST was clearly increased in MCF-7-EMT cells. Protein expression of epithelial marker CDH1 was clearly decreased. With the breast cancer cell lines, MCF-7-EMT and MCF-7 WT cells, we have an excellent model of cells for further studies of EMT and invasion in vitro and in vivo.